Feeling you get the morning after throwing up/ falling over/ talking to the wall about the universe being made out of segments on account on having over-indulged in the drug ketamine.
I thought I threw up on my front doorsteplast night, but when I came round I realised it was my flatmate's bed. Major regretamine.
A phrase that has been ironically quoted by many vtubers after a Twitter user posted screenshots of an alleged vtuber asking for free art saying "I'm a vtuber and you'll regret this" after the artist refused.